Apparatus for spraying wet cementitious materials



W. D. BROWN oct. 19, 1965 APPARATUS FOR SPRAYING WET CEMENTITIOUS MATERIALS I5 Sheets-Sheet 1 Filed NOV. l5, 1961 lill/mul INVENTOR, Vx/dv'rew 27, ,Fray/77 BY /m d Oct. 19, 1965 W- D, BRQWN 3,212,759

APPARATUS FOR SPRAYING WET CEMENTITIOUS MATERIALS Filed Nov. l5, 1961 5 Sheets-Sheet 2 INVENTOR. )df/c 77 ,27. ,Bra zu 77 oct. 19, 1965 w. D. BROWN 3,212,759

APPARATUS FOR SPRAYING WET CEMENTITIOUS MATERIALS Filed NOV. l5, 1961 5 Sheets-Sheet 5 United States Patent C) 3,212,759 APPARATUS FOR SPRAYING WET CEMENTITIOUS MATERIALS Warren Durand Brown, 6328 Dakota Circle, Birmingham, Mich. Filed Nov. 15, 1961, Ser. No. 152,477 30 Claims. (Cl. 259-151) This invention relates to a method and apparatus for mixing and conveying wet cementitious materials or the like. More specifically, the invention relates to means for mixing concrete, mortar or other wet cementitious materials in tank apparatus and for transferring the mixed concrete, mortar or other wet cementitious material from the tank apparatus to spraying apparatus.

The basic concept of spraying concrete, mortar or other wet cementitious materials is well known in heavy construction work. The wet cementitious materials may be mixed in a tank and sprayed directly therefrom. In some applications the wet material may be mixed in a separate mixing tank and subsequently transferred to a placer or storage tank from which it is sprayed. In either case, it is desirable to obtain as uniform and thorough a mixing of the Wet cementitious material as possible. Most cementitious materials must be mixed so that the constituents are thoroughly and uniformly wetted by water or the like. The amount of water which is used is critical and the use of too little or too much will result in less than optimum results. When cementitious materials have been ideally mixed with Water, the mass of material is relatively stiff and is not easily moved. Consequently, in the spraying of wet cementitious materials, it has been a long-standing problem to obtain spraying apparatus which Would permit the use of Wet cementitious material having the proper consistency and water content, yet still be sufficiently fluid to permit the material to be sprayed into place. The problem is particularly diliicult when the material must traverse a long length of conduit, hose, lor the like, to a nozzle. In many instances, the optimum consistency and water content of the wetted cementitious material did not lend itself to a spray operation and consequently the material was made more fluid than would be ideally desirable.

The spraying of wet cementitious material comprises, in general, the use of a mixing or storage tank having an outlet port in the bottom thereof to which a length of hose or other conduit is connected. A spray nozzle is commonly attached to the end of the length of hose and includes a source of high pressure air or the like to carry the material from the nozzle to the place where it is to be deposited. The tank is constructed so that a pressure force may be applied to the material therein which tends to force it through the outlet opening and the hose to the nozzle. A main problem in transfer of the material from the tank to the nozzle is the frictional resistance offered by the length of hose to the passage of the cementitious material. The frictional resistance is particularly great when a stiff material is used. The term stiff Irefers to the consistency of the material and the water content, and is to be contrasted with a very fluid material having a high water content which would readily flow through a length of hose.

This invention relates specifically to apparatus which is capable of transferring stiff cementitious materials with a minimum amount of frictional resistance. The amount of frictional resistance to the passage of cem-entitious materials through lengths of hose or other conduit is dependent on the internal friction of the material which is a function of Viscosity, on the external surface friction, and on the completeness of the mixing of the material ingredients with one another. Consequently it is desirable to reduce ice the internal friction and external surf-ace friction of the material as much as possible in a manner which will not require any significant variation of the required material consistency and Water content. A complete and uniform dispersion of water through the material is also desirable. If the material is uniformly and completely mixed, then there will be no accumulation of partially wetted material which would impede transfer of the material through a hose to a much greater extent than a thoroughly wetted mixture. The cementitious material must be thoroughly mixed in the tank from which it is conveyed to the nozzle regardless of whether or not the material was originally mixed in the tank or supplied from another mixing tank. Accordingly, mixing means are commonly provided Within the storage tank.

It has previously been suggested that air under pressure be introduced into the storage tank to facilitate transportation of the cementitious material. Consequenlty, in some prior devices, air nozzles have been placed within the tank and adapted to direct a blast of air through the material adjacent to and within the outlet opening in the tank. Such devices were intended to disperse the wet cementitious material in an air stream and thus pneumatically transport the material through a hose. In such devices, the amount of material transported per hour is directly proportional to the amount of air applied. One of the common problems in spraying cementitious materials by such means is the formation of air pockets or gaps in the material in the hose due to uneven dispersal of wet cementitious material in the air stream which results in a pulsating type of delivery of cementitious material from the spray nozzle to the work area. A pulsating delivery of the material at the spray nozzle makes it extremely difficult to build up a uniform coating of wet cementitious materials at the work area and, consequently, it is desirable to obtain a uniform continuous flow of materials from the spray nozzle. The aforementioned provision for air blasts within the cementitious material in the tank often results in an undesirable pulsating effect. In addition, when the material stored in the ltank has been partially sprayed and the level of the material in a tank is correspondingly lowered, the formation of large air pockets in the hose becomes more and more troublesome. It is also common practice to pressurize the tank area above the upper level of the cementitious material so that a force is exerted which tends to drive the material through the outlet opening and into the hose. As the upper surface of the material becomes lower and approaches the outlet opening in conventional equipment, the upper surface tends to be Very unlevel and the pressure in the tank will often force its way through the material and form pockets therein.

An important object of the present invention is to provide new and improved means for uniformly dispersing high pressure air in the form of small bubbles Within a mass of cementitious material to decrease its internal friction (lower its viscosity) and thus facilitate delivery through a hose or conduit. Another object of the present invention is to provide means to reduce the amount of frictional resistance between cementitious materials and transfer hoses or conduits therefor. Still another object of the present invention is to provide new and improved means of mixing cementitious material by the simultaneous mechanical shearing type agitation of and the dispersion of high pressure air within the mass of material prior to transfer to a spraying nozzle. A further object of this invention is to provide cementitious material mixing and spraying apparatus in which the material can be more thoroughly mixed and wetted than in previous apparatus. Still a further object of the present invention is to provide improved storage and mixing means for cementitious materials. In this connection, it is -an object of the present invention to provide new and improved valve means and air delivery means with which high pressure air may be more uniformly dispersed within a mass of cementitious material. Another principal object of this invention is to provide new and improved loading means for loading storage tanks associated with cementitious spraying material equipment. Other objects and advantages of the present invention Will be apparent to those skilled in the art to which this invention relates by reference to the following detailed description and the accompanying drawing wherein:

FIGURE 1 is a side elevational view, in section, showing the preferred form of the present invention;

FIGURE 2 is another side elevational View of the apparatus shown in FIGURE l;

FIGURE 3 is a plan view of the apparatus shown in FIGURE 2 with parts removed;

FIGURE 4 is an enlarged sectional view taken along the line 4--4 in FIGURE l;

. FIGURE 5 is a plan view taken along the line 5--5 in FIGURE 4;

FIGURE 6 is an enlarged detail view, in section, of a portion of the apparatus shown in FIGURE l;

FIGURE 7 is an enlarged detail of another portion of the apparatus shown in FIGURE l;

FIGURE 8 is an enlarged detail view of another portion of the apparatus shown in FIGURE 1; and

FIGURE 9 is a side elevational view, in section, of an alternative embodiment of the present invention. Referring now to FIGURES l and 2, an illustrative embodiment of the present invention is shown to comprise, in general, a mixing tank 10 which is mounted on a torsion type axle 12 as seen in FIG. 3. The torsion type axle has a pair of wheels 14, 16 and a tow bar 18 is provided by which the unit may be moved from place to place. A pair of braces 22, 24 support the tank on the torsion type axle in a vertical attitude and are bolted to spring pads and 21 attached lrotatably to the axle. Spring elements 26, 27 are abuttingly engaged with the spring pads and axle to provide a spring support therefor. Support braces 28 are secured to the front of the tank and extend downwardly for engagement with the ground to support the tank in a stationary position. The tank cornprises a cylindrical shell center portion 29, an upwardly and inwardly curved upper portion 30, and a downwardly and inwardly extending lower conical portion 32. The upper portion terminates in a loading port 34 and the lower portion terminates in a cylindrical outlet conduit 36. The cylindrical conduit 36 communicates with a passage 37 within a coupling member 38 and a sleeve 39 extends therebetween. The coupling member provides an L-shaped conduit which terminates in a reducing flange 40 of the coupling 38. An outlet pipe 42 is securely fastened to the flange 40 by a corresponding flange 44 and suitable fastening means. The end of the outlet pipe is connected to an air injector unit 46. A length of hose 48 is connected to the other end of the air injector unit and terminates in a conventional spray nozzle (not shown). The air injector unit 46 is connected to a high pressure air source through a hose 50, or the like.

Referring now to FIGURE 6, the air injector unit comprises an annular air receiving cavity 51 which communicates with the hose 50 and is defined by the outer casing 52 and a sleeve 53 which is provided with a plurality of outlet ports 54, 55. A rubber sleeve 56 having a radial flange 57 at one end thereof and a metal sleeve 58 having a similar radial flange 59 are secured on a seat 60 in the outer casting by abutting engagement of the end 61 of the sleeve 53 therewith. A plurality of U-shaped slots 62 in the member 58 extend longitudinally in the direction of flow of material from the pipe 42 to the hose 48. The end 63 of the rubber sleeve is free to flex radially inwardly within the slots 62 and open the cavity 51 to the inner periphery of the hose 48 along the beveled surface 64. Accumulated high pressure air in the cavity 51 will be sufficient to radially inwardly distend the rubber sleeve within the slots to permit high pressure air to flow from the conduit 50 and the chamber 51 into the hose 48 at regularly spaced intervals around the periphery thereof. The rubber sleeve has sucient resilience to rapidly fluctuate between a norma-l unflexed position closing the ports 54 to an inwardly flexed position permitting the passage of air through the ports. Consequently, when high pressure yair is delivered into the chamber 51, the air accumulating therein is delivered in a Ipulsating manner into the hose 48.

The lower end of the coupling 38 terminates in a port 70. A bushing 72 is threadably mounted in the port 70. A bearing hub 74 is secured to the bushing 72 by suitable fastening means and extends downwardly through a base plate 76 llxed to supports 24 and 28. A sprocket wheel 78 is rotatably secured within the bearing 74 and is fixedly secured to a drive shaft 80 which extends upwardly through the bushing 72. The drive shaft 80 is rotatably driven by means of a drive chain 82 which is connected to a sprocket wheel 84 in the gear housing 86. The sprocket 84 is mounted on a vertically extending sh-aft 8S which extends upwardly through the base plate 76 and is connected to conventional drive means comprising a speed reducing gear box 90, a clutch 92 and an engine 94 as shown in FIGURE 2. The engine may be of the small gasoline type as illustrated but any suitable power means may be used.

Referring again to FIGURE 1, the driven shaft 80 is connected to the lower end of a hollow shaft 102 through a connecting pin 104 in a conventional manner. The shaft 102 extends vertically and is supported centrally of the tank by radially outwardly extending braces 105, 106 which are fixed to the side of the tank. The braces lare secured at the inner ends thereof to a manifold sleeve 108 which is rotatably mounted about the shaft 102 and located thereon by collar elements 110, 112 fixedly secured to the shaft by suitable fastening means. The shaft 102 is hollow and Iprovides a central passage 114 which terminates at its upper end in an opening 116 adjacent the upper end of the tank. The manifold sleeve 108 comprises an air inlet cavity 118 having an inlet port which is connected to an air passage 122 provided in the brace 106. The brace 106 extends radially outwardly through a coupling unit 124 in the side wall of the tank and the passage 122 is connected by a conduit 125 to a source of high pressure air. The manifold 108 is provided with packing means 126, 127 at its upper and lower ends to confine the flow of high pressure air from the passage 122 into the hollow pipe 102 through passages 128.

A sleeve 130 is coaxially mounted on the lower end 100 of the shaft 102 and is keyed thereto for rotation therewith. A plurality of agitator blades 132 are fixedly mounted on the sleeve 130 and extend radially outward-ly therefrom `so that the ends of the blades are in relatively close proximity to the interior surfaces of the coupling member 38. The agitator blades are disposed in 'a helical pattern around the sleeve to drive material therealong. As shown in FIGURE 8, the blades have flat lower surfaces 134 and curved upper surfaces 136. The blades are vertically inclined 'at an angle of about 30 with a horizontal plane and are vertically spaced along the length of the sleeve. The leading edges 138 of the blades are located above the trailing edges '140 since the shaft 102 and sleeve 130 are normally rotated in the direction of the arrow 142. Consequently, the blades exert a downward force on material in the lower end of the conical section 32 and in the coupling 3S.

A material aerating and diverting structure 144 is mounted above the sleeve circumjacent the shaft 102 and is fixedly secured thereto by a coupling member 147. The aerating and diverting means has a hollow interior 146 and communicates internally with the passage 114 in the shaft 102 through a plurality of ports in the shaft. The aerator has a conical upper surface 148 which extends downwardly and outwardly relative to the shaft 102 and terminates in a central cylindrical section 150. The aerator is further provided with a lower conical section 152 which extends downwardly and inwardly from the cylindrical section 150 toward the shaft 102. The outer peripheral surface of the conical portion 152 is substantially parallel to the inner surface of the conical portion 32 of the tank. The conical portion 152 terminates in a at horizontal surface 154 substantially above the upper end of passage 37. As shown in FIGURES 4 and 5, a plurality of air outlet ports 156 are provided around the peripheries of the conical sections 148 and 152. Each of the outlet ports is provided with an adjacent opening 158 within which conventional fastening means 160- are receivable. At this point it should be noted that housing 144 is normally rotated in the same direction as the arrow 142 in a counterclockwise direction as viewed from above. Valve means 161 are provided for each of the inlet ports and comprise a valve block 162 of rubber or the like which is provided with a depending cylindrical portion 164 along one surface and outwardly extending v flanges 166, 163, 176 on three sides thereof. The central portion of the flange has an inwardly sloping surface 172 for the purpose to be hereinafter described. A backup plate 174 having a U-shaped slot 176 along one end thereof is adapted to be mounted over the rubber block 162 and within the confines of the flanges 166, 163, 170 by the fastening means 160. In the assembled position, the cylindrical portion 164 of the rubber block extends within the inlet port 156 in the aerator and the metal backup plate is positioned with the U-shaped slot over and surrounding the cylindrical Valve portion. The longitudinal axis of the valve assembly is inclined relative to a horizontal plane so that, as the aerator is rotated counterclockwise with the shaft 102, the leading edge of each of the valve means is the secured section and the trailing edge is the ange 166 and surface 172. Furthermore, material in the tank which travels downwardly relative to the aerator means, will first contact the upper fastened edge of the valve unit and subsequently the surface 172. High pressure air is directed from the passage 114 in the shaft into the chamber 146 in the aerator housing. The high pressure air within the aerating housing exerts a pressure on the inner valve surfaces in the outlet ports and distends the rubber valves outwardly within the U-shaped slots to permit high pressure air to escape around the periphery of the valves. The valves are located on the aerator housing so that material moving past the valves in the tank will engage the surface 172 and keep the valve in a at position whereat none of the material can enter the aerator housing through the air outlet ports.

A plurality of agitator blades 180, 152 are provided around the lower conical portion 152 of the aerator and extend outwardly therefrom at substantially right angles thereto. Consequently, the agitator blades also extend substantially perpendicularly to the side wall of the conical portion 32 of the tank. The agitator blades 180 are arranged in an upper row and the agitator blades 132 are arranged in a lower row. The outer ends of the upper row of blades 180 are sheared at an angle of approximately 45 so that the outer surfaces 184 of the blades 181) are substantially vertical and parallel to the outer surface of the cylindrical portion 150 of the aerator. Each of the blades 186, 182 have flat bottom surfaces and curved upper surfaces, and are inclined at an angle of approximately to a horizontal plane to guide material downwardly relatively to the leading edges.

In addition to the agitator blades 180, 182 mounted on the conical surface 152, radially extending agitator blades 190, 192 are fastened to the upper conical portion 148 and extend substantially horizontally therefrom to positions closely adjacent the conical portion 32. The blades 190, 192 have flat bottom surfaces and curved upper surfaces. In addition, the blades are vertically inclined to provide a configuration which will cause downward displacement of material as the blades pass therethrough. An inclination of approximately 3() degrees relative to a horizontal plane provides satisfactory results. The horizontal blades 19t?, 192, the vertical surfaces 184 of the blades 180, the vertical side wall of the cylinder portion 151), and the inner surface of conical wall 32 dene a material pocket or cavity which is substantially triangular in cross section as indicated at 194, 196. The conical surfaces 32 and 148 divert material toward the pocket 194, 196. The blades 190, 192 tend to push the material into the pocket and the blades 180 tend to push material from the pocket. Furthermore, the blades 190, 192 tend to maintain a constant uniform level of material in the pocket and prevent the formation of large air pockets and irregularities in the level of material entering the pocket.

An elongated scraper blade 261) is secured to the end of the agitator blade 192 and has a lower portion 202 which is closely spaced from the conical wall 32 and extends upwardly therefrom and changes into a vertically extending section 264 which is spaced closely adjacent to the lower portions of the cylindrical wall 29. A support arm 2136 is securely fastened at 208 to the upper end of the scraper blade 186. The support arm 206 is securely fastened by any suitable means 210 to a support member 212 which is fixedly secured to the collar 112 and is adapted to rotate with the shaft 102. Consequently, the scraper blade 2114 is rotated with the shaft. An upper scraper blade 216 has a vertically extending portion 21S spaced closely adjacent the upper portion of the cylindrical wall 29 and an inwardly curved portion 219 spaced closely adjacent the curved wall 3i) and terminating adjacent the inlet opening 34. The blade 216 is fastened to a support arm 220 which is secured to a support arm 222 by suitable fastening means 224. The support arm 222 is rigidly fastened to the collar and is adapted to be rotated therewith by the shaft 102. All of the scraper blades and support arms have at outer side and botto-m surfaces, respectively, and curved inner side and upper surfaces, respectively, to facilitate passage of the blades and support arms through the material. It may be seen that the scraper blades 200, 216 cover substantially the entire inner peripheral surface of the tank from the cylindrical section of the aerator to the loading port 32.

A cover member 230 is provided to close and seal the inlet port 32 and comprises a cylindrical portion 232 which is connected to an integrally formed conical portion 234 extending upwardly and inwardly therefrom. The conical portion terminates in a connecting block 236 having a central slot 233 within which a threaded bolt 24) or the like extends. One end of a drag link 242 is provided with a peripheral groove 244 which extends 360 and receives the end of the bolt 2413. Consequently, the cover is rotatable relative to the drag link. A central support shaft 246 is xedly secured to the cover at its upper end and extends downwardly therefrom and is adapted to be slidably received within the opening 116 at the upper end of passage 114 in shaft 102. A drive bar 259 is spaced radially outwardly of the shaft 246 and is fixedly secured at its upper end to the cover plate. The drive bar 250 is rotatably engaged by bracket 254 which is iixedly secured to the shaft 102 and adapted to be rotated therewith. A scraper blade 256 is xedly secured to the drag link 242 and extends downwardly and outwardly therefrom and terminates in a blade surface 25S which lies closely adjacent to and is substantially parallel with the conical surface 234.

A flanged coupling 261i is fixedly mounted in the inlet port 34 and has a peripheral internal groove 262 within which a sealing ring 264 is mounted. An upwardly and outwardly extending conical rim 266 is rigidly mounted on the coupling 260. An upwardly and outwardly extending conical hopper 270 is movably secured to the rim 266 by suitable fastening means 272 and resilient vibration dampening pads 274 for a purpose to be .hereinafter described. The inner end of the conical terminates in a flat transverse surface 280, which is adapted to provide a mating seat for the conical surface 234 when the cover is in its uppermost position. The sealing means 264 provide-d about the periphery of the flange sealingly engages the cylindrical section 232 of the cover in its uppermost position. As shown in FGURE 7, a series of cover scraper units 282 are provided around the periphery of the opening 34 and comprise bracket elements 284 which are xedly secured to the lower surface of the coupling 260 adjacent the opening7 and extend downwardly and inwardly therefrom. Rubber scraping strips 286 are xedly secured along the lower surfaces of the brackets and are provided with inwardly projecting rubber teeth means 288 which are adapted to rubbing- 1y engage the conical surface 234 of the cover as it is moved between the upper sealed position and a lower position indicated by the dot-dash line 290 whereat the port 34 is open to the tank 10. The cover is movable to the lowered position by moving the shaft 246 through the opening 116 into the hollow interior of the shaft 102 and moving shaft 250 into engagement with rotating arm 254. The shaft 246 is closely received within the passage 114 and acts as a piston therein. When the cover is in its -lower position with the drive shaft engaged by anm 254 the cover is rotatable with the shaft 102. When the cover is being rotated by the shaft, it rotates relative to the drag link 242 and the scraper blade 256 attached thereto. The upper sealed position of the cover 230 is attained very shortly after the drive shaft 250 rises out of engagement with arm 254. Consequently, the cover is rotated with the shaft throughout most of the movement between the upper sealed position and the lower open position. As the cover is moved between the upper position and the lower position, it passes through the teeth 28S on the rubber scraping elements which engage the side surfaces thereof and scrape away any excess material clinging thereto. The number and length of the scraping elements may be varied as desired.

A screen 302 may be provided across the upper end of the hopper 270 and a bracket 304 is fixe-elly secured adjacent the upper edge thereof. The bracket 304 pivotally supports a cover control handle 306 at 308. One end of the handle 306 is pivotally secured at 310 to the upper end of the drag link 242 and the other end 312 of the handle may be moved upwardly and downwardly to move the cover 230 between the upper and lower positions. The tank 10 may be filled with material from above by moving the cover 230 to the lower position. In this manner, cementitious material or other material from a readymix truck or the like may be poured directly into the tank. Another material inlet opening may be provided in the wall of the tank by a port 316y and a conduit 318 to receive material from an adjacent mixing tank in a two-tank system such as described in U.S. Patent 2,793,080.

Referring now to FIGURE 2, the air system is illustrated. In order to pressurize the tank after it has been loaded with material, an air inlet conduit 320 extends through the upper curve portion 30 of the tank and is connected through an operating valve 322 and a conduit 324 to a conventional tank pressure regulator 326. An exhaust pipe 328 extends upwardly from the valve 322 so that high pressure air within the tank can be exhausted to the atmosphere. The tank pressure regulator 326 is connected by a coupling 329, a conduit 330, and a coupling 332 to a high pressure air inlet line 334 which is connected to a conventional high pressure source (not shown) Another conduit 336, extending from the coupling 332, connects the high pressure source to the aerator inlet conduit 106 through a pressure regulator 338, a coupling 340, and a control valve 342. The air injector conduit or hose 50 is connected to the coupling 340 through a control valve 344 and conduit 346. Still another conduit 348 connects the high pressure source to a conventional spray nozzle (not shown) through a coupling 350 and a conduit 352. A cond-uit 354 is connected to an air-operated vibrator cylinder 355 through a control valve 356. The vibrator cylinder 355 is adapted to vi-brate the hopper assembly 270J relative to the rim 266 to facilitate passage of material from the hopper into the tank. Vibration of the hopper assembly is possible because of rubber mounting units 274 by which the hopper assembly is secured to the run.

In operation, with the tank 10 ready to be filled or relled, the handle 306 is upwardly actuated to lower the cover 340 to its lowermost position at 290. A fresh batch of concrete or the like kmay be poured from a ready-mix truck or other suitable mixing tank into the hopper assembly 270 through the screen 302. The shaft 102 is continually rotating in the direction o-f the arrow 142 and the cover, in its lowermost position, rotates therewith so that concrete passes from the hopper assembly through the inlet port 34 and down into the tank. The material strikes the conical surface 234 of the cover and is diverted downwardly and outwardly thereby. When sufficient material has been placed in the tank, the cover is raised by downward actuation of the handle and moved upwardly into its closed sealed position. During the greater portion of the upward movement the cover continues to rotate with the shaft, and as the cover passes through the scraper units 282, the material on the conical surface of the cover is removed so that a tight sealing engagement of the cover may be obtained in the upper position. During loading of the tank, any material which which would ten-d to stick to the conical surface of the cover is immediately scraped away by the scraper blade 256 which is continually located closely adjacent the conical surface 234. When t-he cover is moved upwardly into its uppermost position, it is located in sealing engagement with the seal means 264 provided around the flange 260 so that the upper portion of the tank may be pressurized. In addition, the conical surface of the cover moves into abutting engagement with the conical seat 280 provided along the lower end of the hopper. One of the advantages of the particular cover arrangement disclosed is that high pressure air in the upper end of the tank tends to force the cover upwardly by exerting force along the inner surface of the cover. As the cover is moved upwardly, the seal provided by the conical seat becomes tighter so that no air can escape from the tank. Another advantage of the particular cover arrangement is that it is movable downwardly into the tank and completely out of the way of the material being loaded into the hopper assembly. Furthermore, the conical surface of the cover tends to divert the material outwardly within the tank toward the outer peripheral surface and results in a more uniform loading of the tank. Consequently, as the tank is loaded, the material does not tend to peak in the center of the tank with gaps around the outer periphery.

When the tank has been loaded, the cover is closed and the valve 322 is actuated from an open position, whereat air within the tank can be exhausted through the conduit 328, to a closed position whereat high pressure air from the conduit 324 will pass through the conduit 320 -into the upper end of the tank. If the valve 342 is not already open, it is opened to permit high pressure air to pass through the conduit 106 and the passage 122 to the interior 114 of the shaft 102 to fill the aerator chamber 146. The high pressure air in the shaft passage 114 also exerts a lifting force on the end of the shaft 246 of the cover to keep the cover in the uppermost position. It is contemplated that the presence or absence of high pressure air lin the shaft passage may be used to provide for automatic opening and closing of the cover if desired. For example, when the tank 10 is full of material so that the aerator 144 is surrounded thereby, the air cannot escape through the valves 161 Ias rapidly as when the tank is empty. Consequently, the presence of concrete or the like around the aerator increases the air pressure within the chamber 146 and passage 114 and causes a force to be exerted beneath the shaft 246 which will tend to close the cover. When the material in tank is at `a position below the upper conical surface 148 of the aerator so that the valves 161 thereon are exposed, air pressure within the chamber 146 will be dissipated through the valves at a more rapid rate and cause lessening of the pressure within the shaft so that the cover may be opened automatically. The opening of the cover will indicate that additional concrete or other material should be placed within the tank to provide a continuous spray application of the mterial. With the apparatus shown, the opening of the cover may be accomplished either automatically or manually, as desired. When the level of material within the tank reaches a predetermined low position, the tank may be refilled through the top port by lowering the cover 230 or may be refilled through the conduit 31S and the port 316 from an adjacent mixer tank in a conventiionial manner.

When the tank has been filled with material and the high pressure air valve 322 has been opened to pressurize the tank, the high pressure air tends to force the concrete material Idownwardly through the port 37 and into the coupling 38 from where the material is conveyed out through the conduit 42 to the spray hose. The material within the tank is continually agitated and removed from the side walls -by the upper scraper blade 216 and the lower scraper blade 200. The material is guided downwardly within the tank into the conical lower section 32. When the material reaches the conical lower section, it is guided towand the triangular pocket 194, 196 by the conical upper end 148 of the aerator 144 and the conical inner surface of the portion 32. Consequently, the conical surfaces 32 and 14S provide a feed chute which guides the concrete into the chamber 194, 196 and to a feed tunnel dened by the lower conical surface 152 of the aerator and the adjacent conical surface of the portion 32. As the material moves through the feed chute area and into the triangular pocket 194, 196, the blades 190, 192 tend to compact the material therein, reduce any unevenness in the upper level of the material, and eliminates any large :air pockets in the material. As hereinbefore described, the triangular pocket `or space is defined by the inner periphery of the conical wall 32, the lower surface of the agitator blades 190, 192, and a line drawn vertically along the cylindrical periphery 150 of the aerator which lies substantially in the same plane as the truncated side surfaces 184 of the agitator blades 180. As may ybe seen `in FIGURE l, the material moves downwardly from the pocket into rthe tunnel and is forced downwardly into the opening 37 by the agitator blades 180, 182. The blades are inclined as previously described to force the material downwardly when the shaft rotates inthe direction of the arrow 142. As the material reaches the outlet port 37, it is picked up by helical blades 132 and forced downwardly into the coupling 38 and outwardly through a. side opening into the conduit 42.

The mixing, compacting, Iand passage of the material to the conduit 42 is facilitated by aeration of the material. The aerating is accomplished by the introduction of high pressure air in 'the form of a multitude of small bubbles which are dispersed throughout the concrete mass due to the action of the agitator blades 180, 182 within the relatively narrow tunnel defined by the conical walls 32 and 152. The air is introduced through the valves 161 along the surfaces 148 and 152. The agitator blades serve to force the material downwardly into the passage 37 and to additionally allow the air escaping from the valves to be widely dispersed throughout the mass of material. The more widely the air is dispersed, the lower the viscosity and internal friction of the material will be :and the more easily it will move from the tank into the conduit 42 and through the hose to the nozzle. The particular aerator structure and tunnel structure is important in that it reduces the number of air pockets or Pil gaps which are commonly formed in the mass of material in conventional equipment. In prior practice in tanks having an outlet port to convey material to a spray nozzle, the air pressure within the tank and the tendency of the material to stick to the side walls of the tank often causes gaps and large air bubbles to form within the material which will result in a pulsating delivery of concrete through the conduit. If the upper level of the concrete can be maintained substantially horizontal and the material remains in a uniform mass with no large air pockets or vertical depressions, the pulsating effect may be subsbantially eliminated. The provision of the relatively narrow inclined tunnel through which the material must pass and of agitator blades which tend to direct the material into the tunnel maintains a uniform ilow of material through the tunnel even when the level of the total mass of material -is substantially reduced. Consequently, formation of large air pockets by the trapping of some of the high pressure air Within the tank in the material is reduced. The dispersion of the very small air bubbles through the valve means in the aerator is of an entirely different nvature and produces no pulsating effect within the spray hose because of the extremely fine nature of the bubbles. The functions of the aeration bubbles are to increase the iluidity of the material, and to -increase the completeness of hydration and mixing of the concrete material.

The amount of air pressure required within the tank to force the concrete material downwardly and into the spray hose is partly a function of the frictional resistance of the hose, which is of a relatively restricted diameter, to the concrete materials passing therethrough. In the present invention, the amount of air pressure needed can be susbtantially reduced by the use of the air injector means 46 immediately preceding the entry of the material into the hose. It is to be understood that the aerator device and the :air injector can be used separately even though particular advantages may be derived from the combination. When using the air injector device, a multitude of small bubbles are introduced around the periphery of the moving means of material as it enters the hose 4S by the passa-ge of Ihigh pressure air from the chamber 51 through the ports 54 and outwardly along the outer periphery of the rubber sleeve 63. In this manner a film of air bubbles is directed outwardly into the spray hose Varound the periphery of the concrete mass being transferred therethrough. The formation of the bubble film around the periphery of the material greatly reduces the frictional forces developed between the -material and the hose and thus itself substantially reduces the air pressure required to drive the material from the tank and through the hose by means other than reducing the viscosity of the whole mass of flowing material. In some cases I have been able to reduce the air pressure needed to drive the material from the tank and through the hose to the nozzle as much as 50% by the use of either or both of the above described aerating devices. The air from the chamber 51 is delivered past the rubber valve in a pulsating manner so that a multitude of very fine bubbles are formed around the periphery of the mass of material.

An alternative embodiment of the present invention is shown in FIGURE 9 and comprises a similarly shaped tank 400 within which a rotatable Vertical shaft 402 is mounted in a conventional manner similar to that hereinbefore described. A scraper blade 404 is mounted on the shaft and is rotatable therewith. In this embodiment the scraper blade is provided with a rubber outer surface 406 which is adapted to have peripheral engagement with the inner surface of tank to insure that the inner walls are thoroughly scraped. Instead of providing a pair of scraper blades, the blade is formed with a straight portion 412 adapted to extend parallel to the cylindrical central wall of the tank, with a curved upper portion 414 adapted to extend parallel to the upper curved portion of the tank, and a downwardly extending portion 416 adapted to extend parallelly to the lower conical section of the tank. The lower end of the shaft is rotatably supported in a bearing unit 417 which is mounted above the outlet port 418 by a bracket 42d. The bracket 420. The bracket may be in the form of a plurality of spaced radially extending spokes which provide through passages for the concrete. If desired, the shaft rotating motor may be provided on the top of the tank and may be driven by a conventional air motor 434 which is mounted on a bracket 435 fixed to conventional cover plate 436 and is movable therewith from a closed position to an open position. Coupling means 438 are provided between the shaft 402 and a drive shaft 440. The coupling means is illustrated by a coupling sleeve having a vertically extending groove 442 that is adapted to fit over a horizontal extending pin 444 in the shaft 402 in the closed position of the cover. A hollow double come aerator 550 is iixedly secured to the shaft and has upper and lower conical portions 552, 554. A plurality of agitator blades 556 in the form of pipe sections having a plurality of small air ports 553 formed therein are connected to high pressure air in the chamber 560 of the aerator. In addition, a plurality of outlet ports 562 may be provided above the agitator blades around the periphery of the aerator to further disperse air into the mass of material as it slides downwardly in the tunnel provided between the lower conical surface 554 of the aerator and the adjacent conical surface of the tank. A coupling 564 connects the outlet port 418 to the spray hose as hereinbefore described. The alternative embodiment includes additional equipment which is identical to that hereinbefore described and the operation of the apparatus is identical to the hereinbefore described insofar las identical equipment is provided.

Although the present invention is particularly directed to wet cementitious material some of the principles involved may have application in other environments such as the transportation of dry materials. In addition, it is contemplated that other types of mixing or supply tanks may be utilized even through the disclosed design produces particular and distinctively advantageous results. For example, spraying equipment which utilizes pump mechanisms of the screw of piston types might advantageously employ the aerator-impeller device and/or the air injector. Other modications and changes in the details of construction which utilize the principles of this invention are intended to be included within the scope of the appended claims except insofar as limited by the prior art.

What is claimed is:

1. Apparatus for spraying wet cementitious material or t-he like and comprising, tank means for storing a mass of the Wet material, pressure means connected to one end `of said tank means to establish a primary conveying pressure behind the mass of material, an outlet port formed at another end of said tank means, an inwardly extending tapered section formed in said tank means adjacent said outlet port, la hollow rotatable shaft disposed in said tank means, means for rotatably supporting said hollow rotatable shaft in said tank means, scraping means movable along the inside wall of said tank means and shaped and arranged to maintain a substantially uniform surface level behind the mass of material, means movably supporting said scraping means, means to connect a high pressure said source to the hollow interior of said shaft, aerating means connected to said shaft adjacent said inwardly extending tapered section and communicating with the hollow interior thereof, and said aerating means being rotatable with said shaft within said tapered section of said tank means.

2. The invention as defined in claim l and wherein said aerating means comprises a plurality of agitator blades, and said agitator blades having .air ports formed therein to dispense air in said material.

3. In apparatus for spraying wet cementitious material or the like, tank means for storing a mass of Wet material, pressure means connected to one end of said tank means for establishing a primary conveying pressure behind the mass of material, an outlet port formed at another end of said tank means opposite the connection of said pressure means to said tank means, hollow aerating means rotatably mounted in said tank means adjacent said outlet port, means rotatably mounting said hollow aerating means in said tank means, a plurality of air ports provided around the periphery of said aerating means, and valve means mounted 4on the outer surface of said aerating means over said air ports and being operable in response to high pressure air within said aerating means to open said ports and dispense high pressure air into the mass material.

4. In apparatus for spraying wet cementitious material or the like, tank means for storing a mass of wet material, an aerating device rotatably mounted in said tank means, means rotatably mounting said aerating device in said tank means, a plurality of air ports provided around the periphery of said aerating means, valve means mounted on tne outer surface of said aerating means and covering said air ports, said valve means comprising a exible rubber-like member', a depending portion of said rubber-like member extending upwardly therefrom and being adapted to be received within one of said air ports, and means to secure said rubber-like member on said aerating means with said depending portion of said rubber-like member in said one of said air ports and said rubber-like member surrounding said one of said air ports so that high pressure air within said aerating means will tend to move said rubber-like member relative to said one of said air ports to permit high pressure air to escape into said mass of material and so that movement of material in said tank will tend to close said valve means by forcing said depending portion into said one of said air ports.

5. In apparatus for spraying wet cementitious materials or the like, tank means for storing the wet material, pressure means connected to one 4end of said tank, means for establishing a primary conveying pressure behind the mass of material, rotatable shaft means mounted in said tank means, means rotatably supporting said rotatable shaft means in said tank, scraper blade means connected to said shaft means and being rotatable therewith, said scraper blade means lying closely adjacent the outer periphery of said tank means and being mounted and arranged to scrape material from the inner surface thereof, said scraper blade means extending from a point closely adjacent one end of said tank means -to a point adjacent the opposite end of said tank means whereby substantially the entire inner peripheral wall of said tank means is scraped to remove material therefrom during rotation of said shaft means, and an outlet port for the wet material formed at the other end of said tank means opposite the connection of said pressure means to said tank means for dispensing of the Wet material under pressure. v

6. In apparatus for spraying wet cementitious materials or the like, tank means for storing the wet material, pressure means connected to said tank means at one end for establishing a primary conveying pressure behind the `mass of material, outlet means formed at another end of said tank means opposite said pressure means for conveying the wet material from said tank means under pressure, aerating means mounted in said tank means adjacent said outlet means for introducing small amounts of discrete volumes of air into the web cementitious material as it moves to said outlet means under pressure, scraper blade means rotatably mounted in said tank means and having portions lying adjacent the outer periphery of said tank means and being shaped and arranged to scrape material from the inner surface of said tank means toward said outlet means to maintain a substantially uniform surface level behind the mass of material, and means rotatably mounting said scraper blade means in said tank means.

7. Apparatus for spraying cementitious material or the like and comprising, tank means for storing a mass of the material having a central axis, said tank means comprising a cylindrical central section, said cylindrical central section terminating in an inwardly extending tapered section, an outlet port formed at the end of said inwardly extending tapered section, a hollow rotatable shaft disposed along the central axis of said tank means, means to connect a high pressure air source to the hollow interior of said shaft, aerating means connected to the end of said shaft and communicating with the hollow interior thereof, said aerating means being rotatable with said shaft within said tapered section of said tank, and means adjacent said outlet port to disperse air bubbles throughout the mass of material as it passes into said outlet port.

8. The apparatus as defined in claim 7 and wherein said aerating means comprises hollow cone means, said hollow cone means having a tapered surface extending substantially parallel to the inner surface of the tapered section of said tank means, and means provided on said tapered surface and extending outwardly -towards said tapered section of said tank means to agitate material passing therebetween and disperse air therein.

9. The apparatus as defined in claim 8 and wherein said last mentioned means comprises a plurality of agitator blades, and said agitator blades having air ports formed therein to disperse air in said material.

10. The apparatus as defined in claim 8 and wherein said last mentioned means comprises a plurality of blades, said blades extending at substantially right angles between the tapered section of said tank means and the tapered surface of said aerator means, and a plurality of air injection means spaced among said blades to disperse high pressure air into said mass of material as it passes into said outlet port.

11. The apparatus as defined in claim S and wherein said air dispersing means comprises a plurality of air ports provided around the periphery of said aerating means, said air ports being covered by valve means, and said valve means being operable in response to high pressure air within said aerating means to open said ports and disperse high pressure air into the mass of material.

12. The apparatus as defined in claim 11 and wherein, said Valve means is further responsive to the pressure of material passing over said aerating means and said valve means to close said valve means and prevent material from entering said air ports.

13. The apparatus as defined in claim 11, and wherein, said valve means comprise a exible rubber member, a depending portion of said rubber member extending outwardly therefrom and being adapted to be received within one of said air ports, and means to secure said rubber member on said aerating means with said depending portion of said rubber member in said port and said rubber member surrounding said port so that high pressure air within said aerating means will tend to move said rubber member relative to said port to permit high pressure air to escape into said mass of material and movement of material in said tank will tend to close said valve means by forcing said depending portion into said air port.

14. The apparatus as defined in claim 13 and wherein, said rubber member comprises an elongated body portion, means spaced from said depending portion for fastening said valve means to said aerating means, a backup plate to secure said rubber member on said aerating means, a U-shaped slot formed in said backup plate and being located over said depending portion to permit flexing movement thereof between a port closing and a port opening position, and said means for fastening said valve means to said aerating means being located relative to said depending portion so as to be the leading surface of engagement during rotation of said aerating means with material being displaced relative thereto by relative circumferential movement and by downward movement of the material in the tank to the outlet port.

15. In apparatus for spraying wet cementitious material or the like and comprising tank means, a hose for transporting material from said tank means to a spray nozzle, conduit means connecting said hose and said tank means, said tank means having a main body portion and an inwardly extending tapered section, an outlet port provided at the tapered end of said tapered section, said conduit means communicating with said outlet port, shaft means rotatably supported within said tank means and extending within said tapered section, a housing mounted on said rotatable shaft and being rotatable therewith and located within said tapered section, said housing comprising a rst tapered surface on one end of said housing and a second tapered surface on the other end of said housing, said second tapered surface being located substantially parallel to the tapered section of said tank means, and means to move the material in said tank means over the first tapered surface of said housing and along the inner surface of said tapered section of said tank means and between the second tapered surface of said housing to said outlet port whereby the material flowing between the second tapered surface of said housing and the inner tapered surface of said tank means is of uniform consistency and air pockets therein are eliminated.

16. The apparatus as defined in claim 15 and wherein said shaft means extends through said housing and into said outlet port and said conduit means, agitator blades being connected to said shaft means and rotatable therewith within said conduit means and said outlet port, and said agitator blades being disposed in a helical pattern to drive said material through said outlet port and said conduit means into said hose.

17. The apparatus as dened in claim 16 and wherein the end of said shaft means extends through said conduit means, drive means connected to the end of said shaft means, and power means connected to said drive means to rotate said shaft means within said tank means.

18. The apparatus as defined in claim 17 and wherein said shaft means is provided with air passage means, means connecting said air passage means to a high pressure air source, means connecting said air passage means to said housing, and air dispersing means provided in said housing to disperse high pressure air into said mass of material.

19. The apparatus as defined in claim 18 wherein said means connecting said air passage means to said high pressure source comprises an air pipe extending radially outwardly of said shaft means through a side wall of said tank means, manifold means mounted on said shaft means and rotatably receiving said shaft means and connecting said air pipe to said air passage means, support means holding said manifold means relative to said tank means, and sealing means sealing said manifold means relative to said rotating shaft means so that high pressure air from said air pipe passes through said manifold means into said air passage means.

20. The apparatus as defined in claim 15 and wherein scraper blade means are connected to said shaft means and rotatable therewith, said scraper blade means lying closely adjacent the outer periphery of said tank means to scrape material from the inner periphery thereof, and said scraper blade means extending from a point closely adjacent the second tapered surface of said housing to the tapered surface of said tank means whereby substantially the entire inner peripheral wall of said tank means above said housing is scraped to remove material therefrom and direct the material downwardly and centrally in said tank means.

21. The apparatus as defined in claim 20 and wherein said scraper blades are provided with outer rubber scraper portions which have peripheral engagement with the inner periphery of said tank means.

22. In apparatus for spraying cementitious materials, tank means for storing material, an inlet opening for loading material into said tank means, cover means for closing said inlet opening, a rotating shaft provided within said tank means, means to connect said cover means to said rotating shaft for rotation therewith, said cover means being movable from a first position closing said inlet opening to a second position within said tank means to open said inlet opening, said cover means being engageable with said rotating shaft in said second position and during movement therefrom to said first position and being disengaged from said rotating shaft in said first position, and scraper blade means associated with said cover means during rotation thereof with said shaft to clean material from the upper surfaces thereof.

23. The apparatus as defined in claim 22 and wherein said cover means includes a conical upper surface, a conical seat provided above said inlet opening to receive said conical upper surface, and said scraper means being adapted to clean the conical upper surface of said cover means so that said cover means may be completely seated against said conical seat.

24. The apparatus as defined in claim 22 and wherein said rotating shaft has an air passage provided therein, means connected to said air passage to disperse air within the mass of material in said tank means, said means for dispersing air within said tank means being located adjacent the bottom thereof whereby air is dispersed at one rate when said means for dispersing air is covered with material and at another rate when uncovered by material, and said cover means being responsive to the difference between said one rate and said other rate whereby said cover means will be closed when sufficient material is in said tank means to cover said means for dispersing air and whereby said cover means will be opened when there is insufficient material in said tank to cover said air dispersing means.

25. In appanatus for spraying concrete material or the like and comprising tank means for storing material having a substantially vertical central axis, hose means for delivering material to a work area, conduit means connecting said hose means in said tank means, said tank means comprising a central cylindrical portion and having upper and lower inwardly extending conical sections, said lower conical section terminating in an outlet port at the bottom of said tank means, said conduit means being connected to said outlet port and extending vertically downwardly therefrom, a material outlet provided in said conduit means and being c-onnected to .said hose means, a rotatable shaft means mounted in said tank means and extending along the central vertical axis thereof, said shaft means extending through said outlet port and said conduit means and being supported therein by bearing means, drive means to rotate said shaft means within said tank means, an impeller sleeve mounted on the lower end of said shaft means within said conduit means and said tank outlet opening, impeller blades mounted on said impeller sleeve and being rotatable within said conduit means to drive material therethrough, support means to rotatably support said shaft means within said tank, air passage means provided in said shaft means and extending substantially the length thereof, a high pressure air conduit connected to said passage means, a housing mounted on said shaft means adjacent the lower conical section of said tank means, said housing having a downwardly and outwardly tapered conical upper surface and a downwardly and inwardly tapered conical lower surface, said lower surface extending substantially parallel to the adjoining conical surface of said lower conical section of said tank means, a plurality of air ports provided around the periphery of said housing, said air ports Ibeing connected to said air passage in said shaft means to deliver high pressure air into the mass of material in said tank means, valve means controlling the flow of air from said housing into said tank means and preventing ow of material from sai-d tank means into said housing, blade means mounted on the upper portion of said housing and extending radially outwardly therefrom to .a position adjacent the lower conical surface of said tank means to smooth and downwardly deflect material accumulating thereat, a plurality of -agitator blades mounted on the lower conical surface of the housing and extending outwardly therefrom at substantially right angles, the outer edges of said agitator blades being vertically inclined and the side edges of said blades being inclined to push material downwardly, the outer edges of said agitator blades and the side wall of said housing and the lower surface of said blade means and the adjacent inner peripheral surface of the lower conical section of said tank means defining a cavity having a triangular cross sectional shape, and the conical lower surface of said housing and the side surface of the lower conical section of said tank means defining a downwardly inwardly inclined tunnel having parallel side walls connecting the triangular cavity to said outlet opening, a plurality of scraper means mounted on said shaft means and `being rotatable therewith, said scraper means being located closely adjacent the periphery of said tank means above said housing and adapted to remove material from the walls of .said tank means and direct material into the central portion thereof, and means to pressurize said tank to force material downwardly therein into said triangular cavity where said blade means uniformly disperses the material therein and thereafter into said tunnel wherein said agitator blades aerate and downwardly displace said material and thereafter into said outlet opening and said conduit means for delivery to `said hose means.

26. The apparatus as defined in claim 25 and having a cylindrical cavity provided in the upper end of said shaft means, a support shaft slideably received within said cylindrical cavity, cover means mounted on the end of said support shaft, means to secure said cover to said shaft means for rotation therewith, means to move said Cover from an upper non-rotating position to a lower position of rotating engagement with said shaft means, a material inlet port provided in the upper portion of said tank means, and seal means provided around said inlet port to receive said cover means in said upper position and seal said tank means.

27. In apparatus for spraying wet cementitious material or the like, tank means for storing a mass of wet material, pressure means connected to said tank means for establishing a primary conveying pressure behind the mass of material, an outlet port formed at one end of said tank means, rotatable aerating means mounted in said tank adjacent said outlet port, a tapered surface formed on said aerating means and extending toward said outlet port, a plurality of agitator blades mounted on said aerating means and extending outwardly from said tapered surface at substantially right angles thereto, and a plurality of air injection means spaced among said-blades to disperse high pressure air into said mass of material as it passes into said outlet port.

28. In apparatus for spraying wet cementitious material or the like, tank means for `storing a mass of the wet materi-al, pressure means connected to said tank means for establishing a primary conveying pressure behind the mass of material, aerating means rotatably mounted in said tank, shaft means rotatably supporting said aerating means, air passage means formed in said shaft means, an air pipe extending radially outwardly of said shaft means through a side wall of said tank means, manifold means mounted on said shaft means and rotatably receiving said shaft means land connecting said air pipe to said `air passage means, support means holding said manifold means relative to said tank means, and sealing means sealing said manifold means relative to said rotating shaft means so that high pressure air from said air pipe 17 passes through said manifold means through said air passage means.

29. In apparatus for spraying wet cementitious materials, tank means for storing wet material, pressure means connected to said tank means for establishing a primary conveying pressure behind the mass of material, an inlet opening for loading material into said tank means, cover means for closing said inlet opening, means movably -supporting said cover means for movement from a first position closing said inlet opening to a second position opening said inlet opening, means for dispersing ai-r within the material in said tank means whereby air is dispersed from said means at one rate when said means is covered with material and at another rate when uncovered 'by material, and actuating means for causing movement of said cover between said first position and 4said second position responsive to the difference between said one rate and said other rate whereby said cover means will be closed when sufficient material is in said tank means to cover said means for dispersing air and whereby said cover means will be opened when there is insufficient material in said tank to cover said air dispersing means.

30. In apparatus for spraying wet cementitious material or the like, tank means for storing material, hose means for delivering material to a work area, conduit means connecting said hose means and said tank means, said tank means comprising a central portion and an inwardly extending ltapered end portion, said end portion terminating in an outlet port, said conduit means being connected to said outlet port, a material outlet provided in said conduit means and being connected to said hose means, rotatable shaft means mounted in said tank means, drive means to rotate said shaft means within said tank means, impeller sleeve means mounted on the end of said shaft means within said conduit means, impeller blade means mounted on said impeller sleeve means and being rotatable within said conduit means to drive material therethrough, air passage means provided in said shaft means and extending substantially the length thereof, high pressure air conduit means connected to said air passage means, housing means mounted on said shaft means adjacent the tapered portion of said tank means, a tapered surface formed on said housing means adjacent said tapered surface of said tank means, a plurality of air ports provided around the periphery of said housing means, said air ports being connected to said air passage means in said shaft means to deliver high pressure air into the mass material in said tank means, blade means mounted on said housing and extending radially outwardly therefrom to a position adjacent the tapered surface of said tank means to smooth and deflect material accumulating therewith toward said outlet port, agitator blade means mounted on the tapered .surface of said housing means and extending outwardly therefrom at substantially right angles, scraper means mounted on said shaft means and being -rotatable therewith,and means to pressurize sa-id tank to force material past said housing means into said outlet port and said conduit means for delivery to said hose means.

References Cited by the Examiner UNITED STATES PATENTS 662,403 11/00 Edson 261-124 X 1,073,876 9/13 Steedman 51-12 1,127,660 2/15 McMichael 259-151 1,352,206 9/20 Lintern 291-36 1,387,620 8/21 Shailer 291-36 1,404,904 1/22 Spencer 291-36 1,769,275 7/30 Rice 259-147 X 1,877,255 9/32 Sammis 51-12 2,594,072 4/52 Ridley 51-12 2,794,686 6/57 Anselman et al. 302-24 2,897,005 7/59 Wiltse 302-24 2,946,628 7/60 Bauregger 302-24 2,986,383 5/61 Lowry 261-124 3,107,164 1/62 Ayers et al 259-151 FOREIGN PATENTS 1,216,590 11/59 France.

WALTER A. SCHEEL, Primary Examiner.

LEO QUACKENBUSH, Examiner.

UNTTED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,212,759 October 19, 1965 Warren Durand Brown It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 18, for "Consequenlty" read Consequently column 3, line 68, for "casting" read casing column 4, line 29, for "driven" read drive column 5, line 68, for "relatively" read relative column 7, line 2, after "conical" insert hopper column 8, line 13, for "340" read 230 line 32, strike out "which"; column 9, line 13, for "Elteral" read material column l0, line 4l, for "means" read mass column ll, lines 5 and 6, strike out "The bracket 420."; line l7, for "horizontal" read horizontally line 19, for "come" read con-e M, line 34, for "the" read that line 4l, for "through" read though same column ll, line 66, for "said" read air column l2, line 16, and column` 18, 'line 7, after "mass", each occurrence, insert of column 18, line 36, for "3,107,164" read -r v 3,0l7,164

Signed and sealed this 26th day of July 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. APPARATUS FOR SPRAYING WET CEMENTITIOUS MATERIAL OR THE LIKE AND COMPRISING, TANK MEANS FOR STORING A MASS OF THE WET MATERIAL, PRESSURE MEANS CONNECTED TO ONE END OF SAID TANK MEANS TO ESTABLISH A PRIMARY CONVEYING PRESSURE BEHIND THE MASS OF MATERIAL, AN OUTLET PORT FORMED AT ANOTHER END OF SAID TANK MEANS, AN INWARDLY EXTENDING TAPERED SECTION FORMED IN SAID TANK MEANS ADJACENT SAID OUTLET PORT, A HOLLOW ROTATABLY SHAFT DISPOSED IN SAID TANK MEANS, MEANS FOR ROTATABLY SUPPORTING SAID HOLLOW ROTATABLY SHAFT IN SAID TANK MEANS, SCRAPING MEANS MOVABLE ALONG THE INSIDE WALL OF SAID SCRAPING MEANS MOVABLE ALONG THE INSIDE WALL OF SAID TANK MEANS AND SHAPED LEVEL BEHIND THE MASS OF MATERIAL, MEANS MOVABLY SUPPORTING SAID SCRAPING MEANS, MEANS TO CONNECT A HIGH PRESSURE SAID SOURCE TO THE HOLLOW INTERIOR OF SAID SHAFT, AERATING MEANS CONNECTED TO SAID SHAFT ADJACENT SAID INWARDLY EXTENDING TAPERED SECTION AND COMMUNICATING WITH THE HOLLOW INTERIOR THEREOF, AND SAID AERATING MEANS BEING ROTATABLE WITH SAID SHAFT WITHIN SAID TAPERED SECTION OF SAID TABK MEANS. 